ILSpy/AvalonEdit/ICSharpCode.AvalonEdit/Editing/CaretLayer.cs

// Copyright (c) 2014 AlphaSierraPapa for the SharpDevelop Team
// 
// Permission is hereby granted, free of charge, to any person obtaining a copy of this
// software and associated documentation files (the "Software"), to deal in the Software
// without restriction, including without limitation the rights to use, copy, modify, merge,
// publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons
// to whom the Software is furnished to do so, subject to the following conditions:
// 
// The above copyright notice and this permission notice shall be included in all copies or
// substantial portions of the Software.
// 
// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED,
// INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR
// PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE
// FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR
// OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
// DEALINGS IN THE SOFTWARE.

using System;
using System.Windows;
using System.Windows.Controls;
using System.Windows.Media;
using System.Windows.Media.Animation;
using System.Windows.Threading;

using ICSharpCode.AvalonEdit.Rendering;
using ICSharpCode.AvalonEdit.Utils;

namespace ICSharpCode.AvalonEdit.Editing
{
	sealed class CaretLayer : Layer
	{
		TextArea textArea;
		
		bool isVisible;
		Rect caretRectangle;
		
		DispatcherTimer caretBlinkTimer = new DispatcherTimer();
		bool blink;
		
		public CaretLayer(TextArea textArea) : base(textArea.TextView, KnownLayer.Caret)
		{
			this.textArea = textArea;
			this.IsHitTestVisible = false;
			caretBlinkTimer.Tick += new EventHandler(caretBlinkTimer_Tick);
		}

		void caretBlinkTimer_Tick(object sender, EventArgs e)
		{
			blink = !blink;
			InvalidateVisual();
		}
		
		public void Show(Rect caretRectangle)
		{
			this.caretRectangle = caretRectangle;
			this.isVisible = true;
			StartBlinkAnimation();
			InvalidateVisual();
		}
		
		public void Hide()
		{
			if (isVisible) {
				isVisible = false;
				StopBlinkAnimation();
				InvalidateVisual();
			}
		}
		
		void StartBlinkAnimation()
		{
			TimeSpan blinkTime = Win32.CaretBlinkTime;
			blink = true; // the caret should visible initially
			// This is important if blinking is disabled (system reports a negative blinkTime)
			if (blinkTime.TotalMilliseconds > 0) {
				caretBlinkTimer.Interval = blinkTime;
				caretBlinkTimer.Start();
			}
		}
		
		void StopBlinkAnimation()
		{
			caretBlinkTimer.Stop();
		}
		
		internal Brush CaretBrush;
		
		protected override void OnRender(DrawingContext drawingContext)
		{
			base.OnRender(drawingContext);
			if (isVisible && blink) {
				Brush caretBrush = this.CaretBrush;
				if (caretBrush == null)
					caretBrush = (Brush)textView.GetValue(TextBlock.ForegroundProperty);
				
				if (this.textArea.OverstrikeMode) {
					SolidColorBrush scBrush = caretBrush as SolidColorBrush;
					if (scBrush != null) {
						Color brushColor = scBrush.Color;
						Color newColor = Color.FromArgb(100, brushColor.R, brushColor.G, brushColor.B);
						caretBrush = new SolidColorBrush(newColor);
						caretBrush.Freeze();
					}
				}
				
				Rect r = new Rect(caretRectangle.X - textView.HorizontalOffset,
				                  caretRectangle.Y - textView.VerticalOffset,
				                  caretRectangle.Width,
				                  caretRectangle.Height);
				drawingContext.DrawRectangle(caretBrush, null, PixelSnapHelpers.Round(r, PixelSnapHelpers.GetPixelSize(this)));
			}
		}
	}
}